1. Field of the Invention
The present invention is in the field of manufacture of fine structures for semiconductor contacting, preferably in the form of a band, and particularly for contacting of multi-pole semiconductors such as an integrated circuit having 320 terminals.
2. Description of the Prior Art
Semiconductor chips are usually contacted to system carriers by means of fine wires, these system carriers then being extrusion coated to form housings.
Another method involves the use of prefabricated structures that are referred to as intermediate substrates or "spiders". In this method, known as tape automated bonding, the semiconductor chip first has all of its terminals simultaneously contacted at the inside region of the fine structure. The user than connects it to the wiring by means of the outer region of the fine structure. This format is extremely small, flat and light. It is being increasingly used in multi-pole semiconductor modules wherein contacting in the traditional way is no longer possible or has disadvantages. However, the demands made of the fine structure with modules having a few hundred terminals in the grid measuring less than 150 microns increase to such a degree that they can not be made with standard manufacturing methods.
There are a number of methods available for the manufacture of fine structures, per se. A standard method for the manufacture of what is referred to as a three layer tape is described, for example in "Solid State Technology 3.78 entitled "Beam Tape Carriers--a Design Guide". This method provides for the punching of openings in the adhesive-coated plastic tape onto which the copper is to be laminated. This tape is coated with a photo-resist, exposed with the negative pattern of the fine structure on the copper side, and then developed. The structure is then galvanically coated for example, with tin in the form of a thin structure. After de-coating, the tape is etched with the electrodeposited surface as an etching protection.
The disadvantage in this method is that there is a pronounced bowl or dish formation when laminating the copper over large openings in the plastic tape, thus preventing the precise generation of photo-technical structure. Coating with a photo-resist on the backside of the tape with the openings is likewise not uniformly possible, thus impeding the resist drying and leading later to uncontrolled errors due to popping of the resist and electroplating punch-throughs.
In other known methods, the openings in the plastic tape are produced by etching or dissolving the plastic and the conductor structures may be generated by additional metal build-up.